Arabic Numerals

(No. 15. p. 230.).—Your correspondent should consult Peacock's "History of Arithmetic" in the *Encyclopædia Metropolitana*; and, if he can get them, the notes to Chasles' *Aperçu Historique des Méthodes en Géométric*, and various papers of Mr. Chasles, published in the *Comptes Rendus* of the French Institute. He may perhaps find some information in De Morgan's *Arithmetical Books*, particularly at p. 14.